Device and system for measuring material thickness

ABSTRACT

A piezoelectric sensing device is described for measuring material thickness of target such as pipes, tubes, and other conduits that carry fluids. The piezoelectric sensing device comprises a substrate such as a flexible circuit material, a piezoceramic element, and a solder layer disposed therebetween. These features are arranged in manner that provides a low-profile measurement device suitable for high-temperature applications such as those applications in which the temperature exceeds 120° C. Embodiments of the piezoelectric sensing device can be configured for use as stand-alone units separately located on the target or for use as a string of sensing elements coupled together by way of the flexible circuit material.

This application is a divisional of U.S. patent application Ser. No.12/840,485, filed Jul. 21, 2010, the entire disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to measuring materialthickness using ultrasonic transducers and in one embodiment to apiezoelectric sensing device that comprises a flexible circuit materialand a piezoelectric ceramic.

Several industries (e.g., oil and gas, refinery, chemical, powergeneration) require the transport of fluid (e.g., liquids or gases)through pipes. Nondestructive testing systems can be placed on the outersurface of these pipes to monitor corrosion/erosion of the pipes,including corrosion/erosion on the interior of pipe walls. These systemsare usually implemented as part of manual inspection over the course oftime, wherein the pipe wall thickness and changes in the thickness aremonitored over time. In some cases, the probe or other nondestructivetesting device is permanently coupled to the outer surface of the pipeto continuously monitor corrosion/erosion at that location to determinepipe corrosion/erosion rates and to determine whether that pipe locationis in need of preventative maintenance to prevent a pipe failure.

One example of a nondestructive testing, system used to monitorcorrosion/erosion of a pipe is an ultrasonic testing system. Whenconducting ultrasonic testing of a pipe, an ultrasonic pulse is emittedfrom a probe coupled to the outer surface of the pipe and passed throughthe pipe wall. As the ultrasonic pulse passes into and through the pipewall, various pulse reflections called echoes are reflected hack to theprobe as the pulse interacts with the outer surface of the pipe,internal structures within the pipe wall, and with the back wall of thepipe wall. The echo signals can be displayed on a screen with echoamplitudes appearing as vertical traces and time of flight or distanceas horizontal traces. By tracking the time difference between thetransmission of the ultrasonic pulse and the receipt of the echoes,various characteristics of the pipe can be determined, including pipewall thickness. If the thickness of the pipe wall at the location of theultrasonic testing system decreases over time (e.g., as would be shownbe a reduction in the time of flight of the back wall echo), this can bean indication of corrosion/erosion.

Various factors influence the configuration of devices and in particularthe materials for use in these non-destructive testing systems.Operating conditions such as the operating temperature in someapplications, for example, can exceed the temperature thresholds ofmaterials such as copolymers of polyvinylidene fluoride (PVDF) (e.g.,P(VDF-TrFE)). Processing conditions including temperatures related tocertain processing steps during manufacture are also limiting.Performance factors such as accuracy and sensitivity to small defectsand to small changes in material thickness are other factors thatpreclude the use of particular materials and combinations thereof.However, while improved performance can be achieved using certainconfigurations of materials, these configurations often result inphysical characteristics (e.g., height profile) that limit theapplicability of the resultant devices.

It would therefore be advantageous to provide a device suited forultrasonic testing and measurement of material thickness, with improvedperformance and physical features but that is also configured for highoperating temperatures and high process temperatures.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment a piezoelectric sensing device comprises a substrate,a solder layer disposed on the substrate, and a piezoelectric elementcoupled to the substrate via the solder layer, the piezoelectric elementcomprising a ceramic. In one example of the piezoelectric sensingdevice, the substrate, the solder layer, and the piezoelectric elementare arranged as a layered structure that has a profile height that doesnot exceed 3 mm. In one example o the piezoelectric sensing device, thesubstrate comprises a material that is compatible with operatingtemperatures in excess of 120° C.

In another embodiment a measurement system for measuring materialthickness of a target. The measurement system comprises a substratecomprising a flexible circuit material having an area with an electrodewith a t-shaped geometry. The measurement system also comprises a solderlayer disposed on the electrode and a piezoelectric element disposed onthe solder layer. The piezoelectric element comprising a ceramic bodyhaving a first electrode, a second electrode, and a wrap tab that iscoupled to each of the first electrode and the second electrode. Themeasurement system further comprises a connection for conducting inputsand outputs to and from the piezoelectric element. In one example of themeasurement system, the flexible circuit material, the solder layer, andthe piezoelectric element are arranged as a layered structure that has aprofile height that does not exceed 3 mm.

In yet another embodiment an apparatus for monitoring material thicknessof a target. The apparatus comprises a transducer array secured to thetarget and instrumentation coupled to the transducer array. In oneexample of the apparatus, the transducer array comprises a piezoelectricsensing device, in one example of the apparatus, the piezoelectricsensing device comprises a layered structure that has a flexible circuitmaterial, a solder layer, and a ceramic body coupled to the flexiblecircuit material via the solder layer. In one example of the apparatus,the layered structure has a profile height that does not exceed 3 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the features of the invention can beunderstood, a detailed description the invention may be had by referenceto certain embodiments, some of which are illustrated in theaccompanying drawings. It is to be noted, however, that the drawingsillustrate only certain embodiments of this invention and are thereforenot to be considered limiting of its scope, for the scope of theinvention encompasses other equally effective embodiments. The drawingsare not necessarily to scale, emphasis generally being placed uponillustrating the features of certain embodiments of invention. Thus, forfurther understanding of the invention, reference can be made to thefollowing detailed description, read in connection with the drawings inwhich:

FIG. 1 is a schematic diagram of an exemplary embodiment of ameasurement system.

FIG. 2 is an exploded assembly view of an exemplary embodiment of apiezoelectric sensing device.

FIG. 3 is a side, cross-section, assembled view of the piezoelectricsensing device of FIG. 2.

FIG. 4 is a front view of another exemplary embodiment of apiezoelectric sensing device.

FIG. 5 is a side, cross-section view of the piezoelectric sensing deviceof FIG. 4.

FIG. 6 is a front view of yet another exemplary embodiment of apiezoelectric sensing device.

FIG. 7 is a side, cross-section view of the piezoelectric sensing deviceof FIG. 6.

FIG. 8 is a schematic diagram of an implementation of a piezoelectricsensing device such as the piezoelectric sensing devices of FIGS. 2-5.

FIG. 9 is a schematic diagram of another implementation of apiezoelectric sensing device such as the piezoelectric sensing, devicesof FIGS. 2, 3, 6, and 7.

DETAILED DESCRIPTION OF THE. INVENTION

Referring now to the figures, there is illustrated in FIG. 1 anexemplary embodiment of a measurement system 10 with improved,sensitivity and construction, the latter of which is beneficial forimplementation of the measurement system 10 at operating temperaturesgreater than, e.g., 120° C., and in areas where access by othermeasurement systems is limited. The measurement system 10 can comprise atransducer army 12 and instrumentation 14, which is operatively coupledto the transducer array 12 via a connection 16. The transducer array 12can comprise one or more sensing elements 18, each of the sensingelements 18 having a piezoelectric element 20 coupled to a substrate 22.

Transducer allay 12 can be disposed on a target, such as a pipe, a tube,and related conduits that can be subject to corrosion and erosion by wayof the fluid that is transported therein. The disposition of thetransducer array 12 permits ultrasonic signals generated by thepiezoelectric element 20 to impinge on the material of the target. Theseultrasonic signals are reflected such as by surfaces of the material,wherein the reflected signals are detected by the piezoelectric element20.

In one embodiment, instrumentation 14 can include an ultrasonic testunit 24 that generates waveform pulses (generally, “inputs”), which areapplied to the piezoelectric element 20 via the connection 16. Thewaveform pulses cause a mechanical change (e.g., a dimensional change)in the piezoelectric element 20. This change can cause an acoustic wave,which is transmitted through the material of the target. Conversely, thepiezoelectric element 20 generates a voltage difference when acousticwaves reflected from the material under inspection contact the surfaceof the piezoelectric element 20. This voltage difference is detected asreceive signals (generally, “outputs”) by the ultrasonic test unit 24 orother signal processing electronics.

The ultrasonic test unit 24 can include various control means, which areuseful to determine the amplitude, timing, and transmit sequence of thewaveform pulse generated by the piezoelectric element 20. The waveformpulse is generally in the frequency range of about 5 MHz to about 20MHz. By tracking the difference between the transmission of the waveformpulse and the receipt of the received signal and measuring the amplitudeof the reflected wave, various characteristics of the material can bedetermined. In one example, the thickness of the material of the target,as well as any corresponding changes in the thickness, can be determinedusing time-of-flight analysis, the subject matter of which will berecognized by those artisans having skill in the transducer and relatedarts.

In one embodiment, the sensing elements 18 are separately arranged andare constructed as individual sensing units. Communication between theseindividual units and the ultrasonic test unit 24 is facilitated by theconnection 16, and in one construction the connection 16 has a pluralityof cables (not shown). These cables are coupled to each of the sensingelements 18. Exemplary cables can include coaxial cables and opticalfibers, as well as single and plural strands of copper and/or relatedmaterials that can conduct the inputs and outputs (e.g., the waveformpulses and the received signals) to and from the piezoelectric element20 as contemplated herein.

In another embodiment, the sensing elements 18 are arranged on a commonsubstrate, generally demarcated in the present example with the numeral26. This arrangement is defined by one or more of the piezoelectricelements 20 being disposed on the common substrate 26. The piezoelectricelement 20 of the sensing elements 18 can be spaced apart from oneanother along for example a strip of material, and as discussed in oneor more embodiments below, this material can comprise a flexible circuitmaterial that can conform to the shape of the target. In one example,conductors are incorporated in the flexible circuit material, with eachconductor terminating at the piezoelectric element 20 and at the end ofthe common substrate 26. The connection 16 can include one or moreconnectors (not shown), which are coupled to the conductors, and whichcan be incorporated or otherwise affixed onto the free end. Theconnector can be coupled to a mating connector or other device such as abundle of coaxial cables extending from the ultrasonic test unit 24.This combination can communicate the inputs and outputs between thepiezoelectric element 20 and the instrumentation 14.

The number of the sensing elements 18 in the transducer array 12 canvary, and in one construction the number can vary from one to twenty. Inone particular example the number is fourteen. An alternative selectionof the number can be based on any one or combination of the dimensionsof the target under inspection, the preferred spacing of the sensingelements 18 on the target, and the type of defect being detected. Whenimplemented in connection with the common substrate 26, the spacingbetween the approximate centers of the piezoelectric element 20 can befrom about 10 mm to about 100 mm. Moreover, in implementations where thesensing elements 18 are arranged as individualized units, each can belocated on the target independently of other ones of the sensingelements 18 of the transducer array 12. Thus the space between adjacentones of the piezoelectric element 20 and the location of thepiezoelectric element 20 relative to features (e.g., edges) of thetarget can be optimized for each of the sensing elements 18 as desired.

Although the transducer array 12 is depicted as a linear array (e.g.,wherein the sensing elements 18 form a single row with one or morecolumns) other configurations are also envisioned. In one embodiment,the transducer array 12 can include one or more rows and one or morecolumns of sensing elements 18. In another embodiment, the sensing,elements 18 are arranged in formations that are different that arrays ofrows and columns. By way of example, one formation for transducer array12 can comprise a first row of sensing elements 18 and a second row ofsensing elements 18, wherein the second row is positioned inperpendicular relation to the first row, thus forming a “t” shape.

Focusing now on the construction of the sensing elements 18, referencecan be had to FIGS. 2 and 3. Here there is depicted an exemplatyembodiment of a piezoelectric sensing device 100 which can be deployedas one or more of the sensing elements 18 of FIG. 1. In one embodiment,the piezoelectric sensing device 100 can comprise a substrate 102 and apiezoelectric element 104 with a ceramic body 106. The ceramic body 106can be configured with an electrode 108, a ground 110, and a wrap tab112 constructed of gold plating or comparable conductive material thatis deposited on the ceramic body 106. The substrate 102 can comprise aflexible circuit material 114, shown in this example with a first layer116 and a second layer 118, and with a receiving area 120 that isconfigured to receive the piezoelectric element 104. The receiving area120 can have electrodes 122 for connecting to, e.g., the electrode 108and the ground 110. The electrodes 22 can include a first or groundelectrode 124 and a second or hot electrode 126. The electrodes 122 canconform to an electrode geometry 128 that is defined by an isolation gap130 between the electrodes 122 and/or a shape geometry 132 as applied toone or both of the electrodes 122. In one example the shape geometry 132comprises a t-shaped geometry 134 for the hot electrode 126.

In one embodiment, the piezoelectric sensing device 100 may also includea solder layer 136 that comprises one or more materials such as tin,lead, silver, bismuth, and indium. The solder layer 136 is depositedduring assembly and is used to couple the piezoelectric element 104 tothe receiving area 120 of the substrate 102. When assembled, thecombination of the substrate 102, the piezoelectric element 104, and thesolder layer 136 are arranged as a layered structure 138 with a profileheight P. Embodiments of the piezoelectric sensing device 100 can beconfigured so that the profile height P does not exceed about 7 min, andin one example the profile height is from about 0.25 mm to about 1 mm.These values are smaller than conventional devices, which permits use ofthe piezoelectric sensing device 100 in places that are generally notaccessible with measurement devices of conventional construction.

Materials for use in the ceramic body 106 are selected for theirproperties including for example compatibility with processingconditions during assembly such as the reflow temperatures required toreflow the solder layer 136. These reflow temperatures typically are inexcess of 200° C. and in one exemplary process the ram temperatures isabout 220° C. Other properties to consider include, but are not limitedto, dielectric constant of the material, wherein the materials that areselected for the ceramic body 106 should have a dielectric constant thatrenders good electrical impedance matching, while minimizing the overalldimensions of the piezoelectric element 104. These dimensions include,for example, dimensions for the rectangular shape of FIG. 2 of about 3mm by about 5 mm, although the length and width can vary, respectively,from about 2 mm to about 8 mm. In other examples, the shape of thepiezoelectric element 104 can comprise a square, a circle, and/or anellipse. With reference to the profile height P discussed above, it isfurther contemplated that piezoelectric element 104 is formed with anoverall thickness from about 0.1 mm to about 1 mm.

In one embodiment, it may be desirable to use piezoelectric ceramicssuch as Navy Type II materials and related ceramics (e.g., leadzirconium titanate piezoelectric), although other materials havingsimilar properties and composition are likewise contemplated and may beused. For purposes of constructing the ceramic body 106 (and thepiezoelectric element 104 in general), in one example a brick of NavyType II material can be diced into plates having a thickness on theorder of 0.6 mm. These plates can be finished by way of finish grindingoperations so that the thickness of the resulting plates is about 0.2mm. Linear grinding, lapping, and back grinding are all acceptablefinish grinding operations. The plates can thereafter be cut into stripswith a width of about 9 mm and the electrodes can be formed, poled, andtested. Plating operations such as sputtering can be used to deposit thegold (Au) plating and the finished plates can be diced to form theindividual piezoelectric elements (e.g., the piezoelectric element 104).In one example, a single brick of Navy Type II material can yieldapproximately 2880 of the piezoelectric element 104. It will beappreciated that the electrodes 122 can be formed using certaindeposition, etching, sputtering, and related processing techniques andprocesses recognized within the scope and spirit of the presentdisclosure.

The layers (e.g., the first layer 116 and the second layer 118) of theflexible circuit material 114 can comprise materials such as apolyamide-based film, as well as other materials and films that compriseone or more of polyester (PET), polyimide (PI), polyethylene napthalate(PEN), and polyetherimide (PEI). The layers can be constructed togetherto form a laminate that is compatible with the processing conditions,operating temperatures, and physical characteristics (e.g., the profileheight P) discussed herein. Conductors such as electrical conductorslike Metal foil may be included among the layers, or in other examplesthe conductors can be incorporated amongst the layers such as by usingelectroplating and related plating and deposition techniques. Theseconductors can extend to the electrodes 122 as well as to peripheraledges and areas of the substrate 102. This configuration is useful toconduct the pulse and electrical signals to and from the piezoelectricelement 104, an example of which was discussed above in connection withthe common substrate (e.g., the common substrate 26 of FIG. 1).

Referring next to FIGS. 4-7, there is provided exemplary embodiments ofa piezoelectric sensing device 200 (FIGS. 4 and 5) and 300 (FIGS. 6 and7). For purposes of the discussion that follows below, like numerals areused to identify like components as between FIGS. 2-7, except that thenumerals are increased by 100 (e.g., 100 is 200 in FIGS. 4 and 5, and200 is 300 in FIGS. 6 and 7). The piezoelectric sensing devices 200 and300 are useful for implementation in one or more of the configurationsof the transducer array 12 discussed in connection with FIG. 1 above.

The piezoelectric sensing device 200 that is depicted in FIGS. 4 and 5,for example, is suited for use in connection with the configuration ofthe transducer array 12 (FIG. 1) wherein each of the sensing elements 18is arranged as individual units. In one embodiment, the piezoelectricsensing device 200 can comprise a substrate 202 and a piezoelectricelement 204. The substrate 202 can comprise a flexible circuit material214 with a receiving area 220 in which is positioned the piezoelectricelement 204. The receiving area 220 can have electrodes 222 including aground electrode 224 and a hot electrode 226. A solder layer 236 can bedisposed on one or more of the electrodes 222 using screen printingtechniques recognized in the art.

The flexible circuit material 214 can comprise a frontside 240 and abackside 242 on which are located the electrodes 222. The piezoelectricsensing device 200 can also comprise one or more cable connections 244with cable connection pads 246 and strain reliefs 248. The cableconnection pads 246 can include a ground pad 250 and a hot pad 252, eachbeing coupled to, respectively, the ground electrode 224 and the hotelectrode 226 by way of one or more vias 254. The vias 254 extendthrough the flexible circuit material 214, thereby coupling the cableconnection pads 246 on the frontside 240 to the electrodes 222 on thebackside 242. In one example, a ground plane 256 is also incorporatedinto the flexible circuit material 214. The ground plane 256 is coupledto the ground electrode 224 and the ground pad 250.

The piezoelectric sensing device 300, as depicted in FIGS. 6 and 7, canbe implemented when the transducer array 12 (FIG. 1) utilizes a commonsubstrate (e.g., the common substrate 26 (FIG. 1)). In one embodiment,the piezoelectric sensing device 300 can comprise a substrate 302 and apiezoelectric element 304. The substrate 302 can comprise a flexiblecircuit material 314 with one or more receiving areas 320 configured forreceiving the piezoelectric element 304 thereon. The receiving areas 320can have electrodes 322 including a ground electrode 324 and a hotelectrode 326. A solder layer 336 is also included for securing thepiezoelectric element 304 to the electrodes 322.

The piezoelectric sensing device 300 can comprise a common substrate 358in which a plurality of conductors 360 are incorporated. The conductors360 can include hot conductors 362 and ground conductors 364, each beingillustrated as extending from a free end 366 of the common substrate358. Disposed on the free end 366 is a connector 368 such as a multi-pinconnector that is coupled to each of the conductors 360. The connector368 is likewise configured to couple to a mating connector (not shown)as might be associated with the instrumentation (e.g., instrumentation14 (FIG. 1)) contemplated herein.

Discussing now the implementation of piezoelectric sensing devices suchas the piezoelectric sensing devices 100, 200, and 300 discussed above,reference is now directed to FIGS. 8 and 9. The FIGS. 8 and 9illustrate, respectively exemplary embodiments of a piezoelectricsensing device 400 and 500, these embodiments being configured for usein measurement systems such as the measurement systems described aboveand in more detail below. Like numerals are also used to identify likecomponents as between the FIGS. 2-9. However, although some of thefeatures and concepts of the piezoelectric sensing devices of thepresent disclosure may not be depicted or discussed in connection withFIGS. 8 and 9, it is contemplated that such features and concepts areapplicable to the piezoelectric sensing devices 400 and 500 as well asembodiments and derivation thereof.

There is depicted in FIG. 8, for example, a plurality of piezoelectricsensing devices 400, each of which can comprise a substrate 402 and apiezoelectric element 404. The substrate 402 can include a flexiblecircuit material 414 with a ground electrode 424, a hot electrode 426,and a solder layer 436 that is used to secure the piezoelectric element404 to the substrate 402. The flexible circuit material 414 includes afrontside 440 and a backside 442. In one embodiment, the piezoelectricsensing devices 400 are implemented as part of a measurement system 470,which can comprise a transducer array 472, instrumentation 474, and aconnection 476 such as one or more cables 478 that are coupled to thepiezoelectric element 404. The measurement system 470 can also comprisea connection terminal 480 to aggregate the cables 478, acting in oneexample as a central hub for communicating signals to and from theinstrumentation 474 and the piezoelectric sensing devices 400 of thetransducer array 472.

In one embodiment, the piezoelectric sensing devices 400 are secured toa surface 482 of a target 484 using a couplant 486 such as an adhesivethat is disposed on the backside 442 of the substrate 402. To thrillerensure proper functioning and coupling of the piezoelectric sensingdevices 400 to the surface 482, one or more outer structures 488 can beutilized such as a protective layer 490 and a fastening mechanism 492.These outer structures 488 can be incorporated as part of thepiezoelectric sensing devices 400 or in one embodiment the outerstructures 488 comprise one or more pieces separate from thepiezoelectric sensing devices 400. Assembly of the pieces of the outerstructures 488 can occur at the time of implementation and installationof piezoelectric sensing devices 400 and the measurement system 470generally.

The couplant 486 can be disposed on surfaces of the substrate 402, asdepicted in FIG. 8, as well as on the piezoelectric element 404. Careshould be taken during application to avoid degradation of theperformance of the piezoelectric element 404. In addition to performancecharacteristics, it may be desirable that materials for use as thecouplant 486 are compatible with the material characteristics of thesubstrate 402 and the target 484. In one example, adhesives such asacrylic adhesives can be applied at as a layer with a nominal intitialthickness of about 1 mm. Other adhesives and related materials that maybe likewise acceptable include, but are not limited, to, cyanocrylates,epoxies, solvent-based adhesives, and cold-flow adhesives, as well ascombinations and derivations thereof.

The protective layer 490 is used to prevent damage to the underlyingstructure, e.g., the piezoelectric sensing devices 400. Materials canlikewise have electrically insulating properties thus providingprotection from the outer environment as well as preventing arcing,shorting, and other electrical-induced failures that can occur.Exemplary materials for use as the protective layer 490 can includesilicon, nylon, neoprene, polymeric materials, and combinations andderivations thereof.

The fastening mechanism 492 can be in the form of the band-likestructure illustrated in FIG. 8. When the target 484 is a pipe or othercircumferential device, such structures can be affixed about thecircumference. These structures can incorporate secondary fastening andtightening features that reduce the diameter of the band about the pipe,thereby applying a force onto the piezoelectric sensing devices 400. Forother configurations of the target 484, such as for targets with flat orirregular constructions, the fastening mechanism 492 may be configuredwith devices that are designed for the specific configuration of thetarget 484. These devices may include magnets and magnetized implementsthat can cause to be applied to force onto the piezoelectric sensingdevices 400.

Referring now to FIG. 9, it is seen that the piezoelectric sensingdevice 500 can comprise a substrate 502 and a piezoelectric element 504.The substrate 502 can comprise a ground electrode 524 and a hotelectrode 526, and a solder layer 536 is included as contemplatedherein. The substrate 502 is arranged as a common substrate 558 with afree end 566 on which is disposed a connector 568. The piezoelectricsensing device 500 is part of a measurement system 570, which cancomprise a transducer array 572, instrumentation 574, and a connection576 coupled therebetween. To secure the piezoelectric sensing device500, a couplant 586 is used and further protection is afforded by aprotective layer 590 and a fastening mechanism 592. In one embodiment,the connection 576 can comprise a single cable 594 that is coupled tothe connector 568 and to the instrumentation 574. The single cable 594can comprise, for example, a mating connector 596 that is configured tomate with the connector 568.

This written description uses examples to disclose embodiments of theinvention, including the best mode, and also to enable any personskilled in the art to practice the invention, including making and usingany devices or systems and performing any incorporated methods. Thepatentable scope of the invention is defined by the claims, and mayinclude other examples that occur to those skilled in the art. Suchother examples are intended to be within the scope of the claims if theyhave structural elements that do not differ from the literal language ofthe claims, or if they include equivalent structural elements withinsubstantial differences from the literal language of the claims.

1. A measurement system for measuring material thickness of a target,said measurement system comprising: a substrate comprising a flexiblecircuit material having an area with an electrode with a t-shapedgeometry; a solder layer disposed on the electrode; a piezoelectricelement disposed on the solder layer, the piezoelectric elementcomprising a ceramic body having a first electrode, a second electrode,and a wrap tab that is coupled to each of the first electrode and thesecond electrode; and a connection for conducting inputs and outputs toand from the piezoelectric element, wherein the flexible circuitmaterial, the solder layer, and the piezoelectric element are arrangedas a layered structure that has a profile height that does not exceed 3mm.
 2. A measurement system according to claim 1 further comprising acouplant disposed on one or more of the flexible circuit material andthe ceramic body, wherein the couplant adheres to a surface of thetarget.
 3. A measurement system according to claim 1 further comprisinga protective layer disposed on the flexible circuit material.
 4. Ameasurement system according to claim 1 wherein the flexible circuitmaterial comprises a first layer, a second layer, and a conductordisposed between the first layer and the second layer, and wherein theconnection comprises a connector coupled to the conductor and disposedon a free end of the flexible circuit material.
 5. A measurement systemaccording to claim 1 wherein the connection comprises a cable secured toone or more cable connections incorporated into the flexible circuitmaterial.
 6. A measurement system according to claim 1 furthercomprising instrumentation coupled to the connection, wherein theinstrumentation is configured to transmit inputs to the ceramic body,and wherein the inputs excite the ceramic body.
 7. An apparatus formonitoring material thickness of a target, said apparatus comprising: atransducer array secured to the target; and instrumentation coupled tothe transducer array, wherein the transducer array comprises apiezoelectric sensing device, wherein the piezoelectric sensing devicecomprises a layered structure that has a flexible circuit material, asolder layer, and a ceramic body coupled to the flexible circuitmaterial via the solder layer, and wherein the layered structure has aprofile height that does not exceed 3 mm.
 8. An apparatus according toclaim 7 further comprising a protective layer disposed proximate afrontside of the flexible circuit material.
 9. An apparatus according toclaim 7 further comprising a fastening mechanism operatively configuredto apply a force to the piezoelectric sensing device.
 10. An apparatusaccording to claim 7 further comprising an couplant disposed on one ormore of the flexible circuit material and the ceramic body, wherein thecouplant adheres to the target.